What are the arrays in php?

There are four types of arrays in PHP, namely: 1. Index array, the most basic array type in PHP; 2. Associative array, a commonly used array type in PHP; 3. Multi-dimensional array, which contains multiple An array of arrays; 4. Object array, which can store a set of objects and allow access and operation on each object.

The operating environment of this tutorial: windows10 system, php8.1.3 version, DELL G3 computer.

Arrays in PHP are a very important data type that can be used to store a series of related data. In PHP, arrays not only have traditional indexed arrays, but also have more extended and advanced forms. The following are the various types of arrays in PHP:

Index array

The most basic array type in PHP is the index array. This type of array accesses and operates on array elements based on numerical indexes. In PHP, indexing starts from 0.

The following is a simple example:

$my_array = array("apple","banana","orange");

In this example, the array name is $my_array, which contains 3 elements, namely "apple", "banana" and "orange". Array elements can be accessed and manipulated by specifying the corresponding index within square brackets. For example, to access the first element (i.e. "apple"), we can use the following line of code:

echo $my_array[0];

Associative array

Associative array is another type of array in Commonly used array types in PHP. It is accessed and manipulated similarly to objects in JavaScript.

In an associative array, each array element has a name (also called a key) that is used to access and manipulate that element. The following is a simple example:

$my_array = array("name"=>"Tom","age"=>25,"gender"=>"male");

In this example, $my_array is an associative array containing 3 elements, namely "name", "age" and "gender". In order to access or update an element in an associative array, we need to use the element name as the array index, for example:

echo $my_array['name']; // 输出 "Tom"

Multidimensional array

PHP also supports multidimensional arrays, which contain Array of multiple arrays. This kind of array consists of multiple array elements, and each element can be of any array type (including other multi-dimensional arrays).

The following is a simple example:

$my_array = array(
    array(1, 2, 3),
    array("apple", "banana", "orange")
);

In this example, $my_array is a multi-dimensional array containing 2 elements. The first element is an index array containing 1, 2, and 3, and the second element is an index array containing "apple", "banana", and "orange". In order to access elements in a multidimensional array, we need to use multiple square brackets to specify the index of each dimension, for example:

echo $my_array[1][0]; // 输出 "apple"

List

A list is a special type of array that only Can store indexed arrays, and only supports numeric indexes. One of the interesting properties of a list is that it can be destructured into variable names, allowing easy access to its elements.

The following is an example:

$my_array = array("apple", "banana", "orange");
list($fruit1, $fruit2, $fruit3) = $my_array;
echo $fruit2; // 输出 "banana"

In this example, we use the list() function to deconstruct the 3 elements in $my_array into $fruit1, $fruit2 and $fruit3 variables respectively. Contains the values ​​of the "apple", "banana" and "orange" elements respectively. Then we output the value of variable $fruit2, which is "banana".

Object array

In PHP, we can also use the object array type. This type of array can store a set of objects and allow access and manipulation of each object.

The following is a simple example:

class Fruit {
  public $name;
  public $color;
}
 
$my_array = array(
  new Fruit("apple", "red"),
  new Fruit("banana", "yellow"),
  new Fruit("orange", "orange")
);
 
echo $my_array[1]->name; // 输出 "banana"

In this example, we first define a class named "Fruit" and then create an array of objects in which each element contains Two properties (name and color). In order to access the elements in this array, we need to use the arrow operator -> to access the properties of the element. For example, to output the name of the second element (i.e. "banana"), we use the following line of code:

echo $my_array[1]->name;

Summary

Arrays in PHP are a very important data type, Can be used to store a series of related data. In PHP, we have multiple array types available, including basic indexed arrays, associative arrays, multidimensional arrays, lists, and object arrays. Each array type has its own characteristics and uses, so it is very important for programmers to understand these array types.

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